I'm still on InDesign CS [1] so maybe there's something since then, but as far as I know the background of a document has no colour until you put a text or other box on it and make that some colour. If you want all pages to be a certain background colour, you could put the boxes (frames) on the master pages. There must be a way to do this with layers too.

One thing that baffles me about InDesign is that they have a swatch for "None" which is obviously no color, and then a swatch called "Paper" which is also no color but seems to want to be white, although you can change it. It's different from the None swatch because it's opaque, hence white. I don't understand why they don't just call it "White". You can't modify the Black swatch, it's just black, but you can modify this Paper swatch. You can also create a similar no color swatch and name it White for simplicity's sake.

I'm really not at all clear what you want to do, but can't you create a "character style" with your background color and apply it thru the Character Style pane? What background color are you referring to - the page background or the background of the text box?

If you make a little text box of the height you want it, make it the background colour you want, and make the text in it the same style as in your document, you can paste it into your document (with the text tool selected) wherever you need this highlighted text. Then in this little box type the word or words required, and adjust the length of the box as necessary (easiest if you centre the word horizontally in the box). You'll have to shift the box down (it pastes in on the baseline) and adjust the text in it if necessary using baseline shift. The highlighted box will move with the text if you reflow it, though it won't break for a hyphenation. You can copy and paste the box to other places and replace the words.

A bit cumbersome I know. If you know there won't be reflow, just put a coloured box behind the word(s) you want highlighted.

English is not my native language. Forgive me if I was unclear. Gary Long describes what I'm trying to do. Until now I've just placed a box behind the words I want to highlight, but when you're working with large projects it just takes to much time.

There’s a simpler workaround: Create a character style with an ‘underline’ (I don’t know how this option actually is called in English, but I hope you get the point), adjust its stroke width (full line-height or what you want), and its position (shift it upwards). Additionally, you then can assign a shortcut for this character style, and there you go.

Because you (usually) don’t print white.
Yet, you always have a paper (or surface) to print on. So, in case you’ll print on coloured paper – be it yellow or light blue, you name it – you already can get a better impression, without having to create an extra coloured box in the background …

Yet, you always have a paper (or surface) to print on. So, in case you’ll print on coloured paper – be it yellow or light blue, you name it – you already can get a better impression, without having to create an extra coloured box in the background

Isn't this the purpose of having "None" as your background color then? I do use white backgrounds sometimes.

Geez, I'm glad I checked this post out. I had NO idea how to high light single words in a text box. The underline trick is sweet. I'm actually surprised there isn't a "highlight" feature though. For as little as I use strikeout or underline, you'd think it be easy to create a simple customizable feature like "highlighting".

Also, the title of this post should be changed to reflect the content, "background-color" is confusing and for anyone searching for how to highlight in InDesign, this post probably won't come up.

A standard highlight-feature just doesn’t compute — there are a lot of variables (Hq-height in relation to typesize, etc.), so one has to eyeball the values of underline and offset.

I disagree, I think it would be quite easy.

Isn't there an invisible box around each character that determines: leading, tracking and other character changes? If you apply the highlight to that invisible box (in essence making it visible) then if you change any qualities of that character such as size, leading, tracking or offset, the highlighting will automatically change with it. And Underline and Strikeout prove; it's easy to apply character specific, manually augmentable features.

I'm just speculating of course. Either way, you'd still have to manually tweak the end result to really get it to perfection.